Operative treatment of LSVC
The surgical treatment of UCSS depend on the type of the CS septal defect, but depend more on the presence of LSVC and the communication between RSVC and LSVC, that is, more likely based on whether LSVC can be ligated. The ligation criteria in this series of patients was that when obstructing the LSVC, the clamped pressure was not higher than 16 mmHg, and no cyanosis and venous engorgement occurred in the left side of the neck, then LSVC can be ligated. There were reports of the ligation when central venous pressure was less than 30mmHg, although right upper limbs and fontanelle edema occurred in early postoperative period. The patients recovered in a few weeks, and had no neurological complications [13].For those who have UCSS without LSVC or with LSVC that can be ligated, it only need to repair ASD and close the CS opening, or separate the CS opening to the LA when repairing the ASD by the patch, which resulted in a small amount of right-to-left shunt that had no conspicuous physiological effects. The right-to-left shunt caused by pure UCSS only accounted for 4% to 5% of the total blood flow. The impact was very small, and no symptoms or cyanosis occurred. In our series, 8 cases (type I 4 cases, type Ⅲ 1 case, type Ⅳ 3 cases) underwent direct ligation of LSVC, the method is simple and effective, and no complications occurred after operation.
When associated with LSVC that can’t be ligated, the LSVC is rerouted to the right atrium, and different types of CS septal defect require should be treated differently: (1) Intracardiac treatment: baffling or tunneling in the LA to drain the LSVC to the right atrium, and repair the septal defect [Fig 2]; (2) Extracardiac treatment: there are several ways: LSVC-right atrium connection, LSVC-RSVC connection, LSVC-left pulmonary artery connection[14-16]. The intracardiac treatment is the most classic method. Of the series 59 cases with UCSS underwent the left atrial tunnel, 22 intracardiac baffle repair, 4 of which died after the operations, all associated with complex cardiac abnormalities and severe pulmonary hypertension and died of postoperative pulmonary infection. Sixty-five cases were followed up after the operation, no death and complications occurred. In the case of LSVC returning directly to the LA, LSVC often joins the LA anterior to the left atrial appendage and the left pulmonary vein. The left pulmonary vein opening should be noted during the operation so as to avoid obstruction of the left pulmonary vein. Intracardiac treatment required a long operation time, with long duration of myocardial ischemia and postoperative complications such as baffle residual shunt, patch damage, LSVC reflux obstruction, pulmonary venous obstruction, left ventricular inflow tract obstruction and so on. In addition, the disadvantages of intracardiac approach are more obvious for complex congenital heart disease or younger children with small LA. At this point, some authors believe that an extracardiac approach might be better for correcting LSVC ectopic drainage [14]. When LSVC is fully dissociated, connect it to the right atrium or RSVC through the anterior or posterior aorta. Gore -Tex artificial blood vessels have also been reported to successfully connect the LSVC to the right atrium [15]. However, this method is not commonly used, because it may cause obstruction of the superior vena cava or obstruction of the artificial blood vessel after operation which result from the compression of the large vessels or the sternum.
The surgical indication of LSVC connection with the left pulmonary artery is the same as bidirectional Glenn shunt, and for cases associated with pulmonary hypertension, this procedure is not appropriate. Therefore, to deal with cases of LSVC directly drained to the LA, we would highly recommend the choice of intracardiac method of rerouting LSVC, if the surgery is found difficult or ineffective, then the extracardiac treatment would be an alternative method.
The operative effect of intracardiac tunnel in our series is good. The key lies in careful design and operative techniques, and it is still the mainstream treatment, while the external cardiac method is suitable for few cases, so we should choose carefully.